A rotary electronic component is known in which a portion of an outer periphery of a rotary body of is exposed as an operating portion to the outside through an opening provided on an outer case, and an electrical function portion in a main case is driven by rotationally operating the operating portion with a finger etc. so as to cause a change in an output from the electrical function portion. In the rotary electronic component, a drip-proof structure of an electronic component is known in which a rubbery drip-proof sheet is installed so as to seal a gap between the opening and the rotary body to prevent a liquid from entering through the gap between the opening and the rotary body to contact with the electrical function portion (see, e.g., JP 2011/134573 A).
Another drip-proof structure of an electronic component is known in which an electrical function portion is covered with a waterproof case etc. to prevent liquid from contacting with the electrical function portion (see, e.g., JP 2010/9937 A).